PALO is a phosphorylated molecule and does not cross cell membranes easily. We propose to encapsulate PALO in liposomes and thereby introduce PALO into liver cells, hepatocytes, and other cells in tissue culture. We hope to be able to establish a primary culture of liver cells which maintains the urea-cycle enzymes and then study the effects of PALO with these cells. We are also going to investigate effects of PALO in vivo by injecting PALO-liposomes into rats or mice. Further characterization of porcine liver and E. coli OTCases will be carried out. We are going to examine the active center of these enzymes using reagents which attack arginine residues and also investigate the cysteine involvement of these enzymes. Experiments concerning effects of dietary amino acids on urea cycle enzymes will be investigated in both weanling rats and neonatal piglets. We are also going to investigate the nature of the cytoplasmic form of OTCase in terms of its molecular weight and N-terminal or C-terminal peptides as well as the cross-reactivity with antibodies prepared against the mitochondrial enzyme.